Co-Cxny Embedded in N-Doped Carbon as Robust Catalysts for the Synthesis of Γ-Valerolactone from the Hydrogenation of Levulinic Acid Under Low Hydrogen Pressure

Abstract

The rational design of non-noble metal catalysts for the highly efficient production of γ-valerolactone (GVL) from the selective hydrogenation of levulinic acid (LA) at mild reaction conditions is still a big challenge. In this work, the Co embedded in N-doped carbon as a robust catalyst is fabricated by in situ carbonizing ZIF-67 for the selective hydrogenation of LA to GVL. Several catalysts that differed in pyrolysis temperatures and preparation methods were prepared and evaluated. The optimal catalytic performance is achieved with Co@NC-800H, which realizes a up to 99% yield of GVL at low temperature of 120 o C and low hydrogen pressure of 0.5 MPa. Also, the optimal Co@NC-800H catalyst exhibits excellent reusability. By the careful characterizations with multiple techniques, including BET, XRD, SEM, TEM, XPS and Raman, it is found that the excellent catalytic performance of Co@NC-800H is achieved through the synergistic catalysis between oxygen vacancies and Co-C x N y sites.

Keywords: ZIF-67, Levulinic acid, γ-Valerolactone, Oxygen vacancies, Co-CxNy